In this protocol, we seek to assess whether tumor motion can be inferred using dynamic MRI and external surrogates. We propose to (1) investigate the feasibility of tracking the real-time tumor position using dynamic MRI and inferring tumor position using external surrogates placed on the skin of the subject and (2) determine lung function during and following radiation by assessing lung perfusion maps obtained via dynamic MRI with dose maps in order to determine image-based biomarkers for lung toxicity following radiation therapy.